Lab 2 Flashcards

1
Q

Analogous

A

when a similar character in two or more tax is not a result of a common ancestor but instead of convergent evolution (e.g. wings of an insect and wings of a bird)

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2
Q

Ancestral (or plesiomorphic) Character State

A

a character state that was seen in the early ancestors of an organism (e.g. reptiles having four legs)

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3
Q

Branch

A

a line on a phylogenetic tree that connects a node to a terminal taxon

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4
Q

Character

A

some observable features of an organism
it can be morphological, molecular, developmental, physiological, behavioural, or ecological (e.g. either presence or absence of legs)

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5
Q

Clade

A

a lineage that arose for one ancestor (a monophyletic lineage)

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6
Q

Cladogram/Phylogeny/Phylogenetic Tree

A

a tree structure that represents the evolutionary relationships within a group of organisms (three terms are interchangeably)

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7
Q

Convergent Evolution

A

occurs when similar characters evolve independently in two or more texa

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8
Q

Character State Reversals

A

occur when a derived character reverts to an ancestral condition

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9
Q

Derived (or apomorphic) Character State

A

a character state that was not seen in the early ancestors of an organism (e.g. limblessness of snakes )
a modified character state (with reference to another, ancestral, character state)

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10
Q

Homologous

A

when a character in two or more taxa can be tracked back to the character in their common ancestor, or where one character state in a taxon is derived from that in another (i.e. similarity resulting from common descent)

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11
Q

Homoplasy (-ies)

A

similarities in characters of different species resulting from convergent evolution and/or character state reversals, and not resulting from common descent

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12
Q

Ingroup

A

the group that is now being analyzed

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13
Q

Internode

A

a line on a phylogenetic tree that connects two nodes

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14
Q

Monophyletic Group (also called a Clade)

A

a phylogenetic lineage composed of two or more taxa including the common ancestral taxon and all descendants

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15
Q

Node

A

a branching point on a phylogenetic tree or cladogram that represents a speciation event in which one ancestral taxon gave rise to two distinct descendant taxa
branches above the node can be rotated without changing the relationship of the taxa

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16
Q

Outgroup

A

a group that is thought to be closely related to the ancestor of the ingroup, but is not part of the ingroup (snakes and lizards)

17
Q

Paraphyletic Group

A

a group composed of the common ancestral taxon and some, but not all, descendants

18
Q

Parsimony

A

the scientific preference for the simplest possible explanation that will explain some data

19
Q

Polyphyletic Group

A

a group that does not include the common ancestor

20
Q

Sister Group

A

a grouping on a phylogenetic tree where two groups are more closely related to each other than any other group

21
Q

Synapomorphy

A

a shared, homologous, derived character state (e.g. all snakes are limbless, so limblessness is a synapomorphy for snakes)